1. Field of the Invention
The present invention relates to compressor-controlling device and method for an air conditioner comprising a plurality of compressors, and more particularly to compressor-controlling device and method for an air conditioner comprising a plurality of compressors, so that the lowering of an oil level within non-operating compressors is prevented, thereby protecting the compressors from damage due to poor lubrication.
2. Description of the Related Art
Generally, an air conditioner comprises a compressor for compressing a gaseous refrigerant in a low-temperature and low-pressure state so as to convert it into a high-temperature and high-pressure state, a condenser for condensing the gaseous refrigerant in the high-temperature and high-pressure state compressed by the compressor so as to convert it into a liquid refrigerant in a mid-temperature and high-pressure state, an expansion device for decompressing the liquid refrigerant in the mid-temperature and high-pressure state condensed by the outdoor heat exchanger so as to convert it into a low-temperature and low-pressure state, and an evaporator for evaporating the liquid refrigerant in the low-temperature and low-pressure state decompressed by the expansion device so as to convert it into a gaseous refrigerant in a low-temperature and low-pressure state.
In case of a heat-pump air conditioner, an indoor heat exchanger and an outdoor heat exchanger respectively serve as different means according to cooling and heating modes. In the heating mode, the indoor heat exchanger serves as a condenser and the outdoor heat exchanger serves as an evaporator. On the other hand, in the cooling mode, the indoor heat exchanger serves as an evaporator and the outdoor heat exchanger serves as a condenser.
Further, recently, air conditioners have employed a plurality of compressors having different capacities so as to variably change the total capacity of the compressors according to the variation of the cooling or heating load.
In the conventional air conditioner comprising plural compressors, in case several compressors selected from the plural compressors are operating according to the cooling or heating load and the other compressors have stopped for a long period of time, the refrigerant contained in a high-pressure state inside of the stopped compressors moves toward a refrigerant pipe of a lower-pressure inlet port, and oil used to operate the compressors leaks toward the inlet port. Thereby, an oil level within the stopped compressors is lowered, and when the stopped compressors are operated, the compressors are damaged due to poor lubrication.